As medical device technologies continue to evolve, neurostimulator devices have gained much popularity in the medical field. Neurostimulator devices are electrically-powered devices (e.g., battery-powered) that are designed to deliver electrical stimulation to a patient. Through proper electrical stimulation, the neurostimulator devices can provide pain relief for patients. The medically accepted mechanism for pain relief is known as “gate control theory,” which theorizes that the nervous system has a “gate” that closes and prevents the passage of pain signals if it is presented with sufficiently strong sensory signals. As a result, the patient may feel only a tingly sensation—also known as paresthesia—instead of pain in the area that is stimulated.
A typical neurostimulator device may include one or more integrated circuit chips on which the control circuitry and neurostimulation circuitry are built. The neurostimulator device may also include a plurality of electrodes that are in contact with different areas of a patient's body. Controlled by the control circuitry, the electrodes are each capable of delivering electrical stimulation to their respective target contact areas. Thus, the patient can use the neurostimulator device to stimulate areas in a localized manner.
Although neurostimulator devices have been proven to be useful, existing neurostimulator devices may still suffer from one or more shortcomings. For example, many existing neurostimulator devices can turn on and off each electrode, but they lack the capability to individually control the amount of electrical stimulation given by each electrode. As another example, some existing neurostimulator devices may require a large number of transistors to implement the neurostimulation circuitry. These transistors consume a significant amount of integrated circuit chip area and consequently drive up the fabrication costs of neurostimulator devices.
Therefore, while existing neurostimulator devices have been generally adequate for their intended purposes, they have not been entirely satisfactory in every aspect.